The Austin-based grocer spent seven months studying the sale of live lobsters from ship to supermarket aisle, trying to determine whether the creatures suffer along the way.

In some stores, they experimented with "lobster condos," filling tanks with stacks of large pipes the critters can crawl inside. And they moved the tanks behind seafood counters and away from children's tapping fingers.

Ultimately, Whole Foods management decided to immediately stop selling live lobsters and soft-shell crabs, saying they could not ensure the creatures are treated with respect and compassion.

"We place as much emphasis on the importance of humane treatment and quality of life for all animals as we do on the expectations for quality and flavor," John Mackey, Whole Foods' co-founder and chief executive, said in a statement.

Animal rights activities were thrilled with the decision, not just because of the way lobsters are harvested, shipped and stored but because of the fate that awaits many of them — being dropped alive into a pot of boiling water.

But other scientists and seafood industry officials said Thursday that lobsters have such primitive insect-like nervous systems they don't even have brains and can't experience pain the way animals and humans do.

For example, lobsters can shed a claw that's stuck between two rocks and move on like nothing happened, said Diane Cowan, a marine biologist who studies lobster behavior in Maine.

"They certainly have a nervous system and respond to external stimuli, but whether you can call it pain I don't know," Cowan said.

About 183 million pounds of lobster are caught each year in the United States and Canada, and about 25 percent of that is sold live, according to the Lobster Institute at the University of Maine.

"People who want lobster will have lobster," said Bill Adler, executive director of the Massachusetts Lobstermen's Association. "If this particular chain does not want to serve it, people will go elsewhere."

From now on, Whole Foods will only sell frozen raw and cooked lobster products at its more than 180 stores in the United States, Canada and the United Kingdom, said Margaret Wittenberg, vice president of quality standards. And the chain will only deal with suppliers meeting their standards for humane treatment, handling and processing.

Whole Foods leaders will reconsider the decision if they see evidence that it's possible to ensure lobsters and crabs are treated humanely throughout the supply chain, she said.